@ ProgramNode (location: (1,0)-(2,1))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(2,1))
    └── body: (length: 1)
        └── @ CallOrWriteNode (location: (1,0)-(2,1))
            ├── flags: safe_navigation
            ├── receiver:
            │   @ CallNode (location: (1,0)-(1,1))
            │   ├── flags: variable_call, ignore_visibility
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── name: :a
            │   ├── message_loc: (1,0)-(1,1) = "a"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   └── block: ∅
            ├── call_operator_loc: (1,1)-(1,3) = "&."
            ├── message_loc: (1,3)-(1,4) = "b"
            ├── read_name: :b
            ├── write_name: :b=
            ├── operator_loc: (1,5)-(1,8) = "||="
            └── value:
                @ CallNode (location: (2,0)-(2,1))
                ├── flags: variable_call, ignore_visibility
                ├── receiver: ∅
                ├── call_operator_loc: ∅
                ├── name: :x
                ├── message_loc: (2,0)-(2,1) = "x"
                ├── opening_loc: ∅
                ├── arguments: ∅
                ├── closing_loc: ∅
                └── block: ∅